This invention relates generally to methods and medical apparatus and in particular to methods and apparatus for modifying health-related behavior, such as weight control for diabetes or general health. More particularly the invention relates to apparatus for analyzing medically significant components in exhaled breath.
Diabetes is a chronic disease affecting many organs and body functions. The disease is caused either by a lack of the hormone insulin or by the body""s inability to use insulin. Diabetes is the most common endocrine disorder. In the United States, for instance, as many as 10 million persons have diagnosed diabetes mellitus, and it has been estimated that an additional 10 million may have the disease without diagnosis. Although there is no cure, most cases can now be controlled adequately by a combination of medication and life style modification, including exercise, diet and weight loss.
Unfortunately, many people with diabetes have difficulty coping with the constraints that the disease puts on their lives. People find it difficult to lose weight, to maintain weight loss, to exercise regularly, to regularly take drugs, or to self-administer tests for blood glucose levels. In general, patients do not receive sufficient positive support for their efforts and can become discouraged. They experience xe2x80x9cdiabetes burn-outxe2x80x9d, a feeling of hopelessness or powerlessness that contributes to abandoning efforts to manage their disease. People who are simply overweight or obese can experience similar barriers when attempting to control their diet and weight. See, for example, Diabetes Burnout, What to Do When You Can""t Take It Anymore, W. H. Polonsky, 1999, American Diabetes Association.
Weight loss is particularly difficult to sustain. Preferably, for weight loss, caloric intake should be reduced to produce an energy deficit of about 500 Calories daily, which usually results in the loss of about one pound of body weight per week. Experts frequently recommend that the body weight be monitored weekly during the process of weight loss. Daily variation in water content of the body and lack of sensitivity of most scales tend to mask any true change. Moreover, contemporaneous improvement in muscle tone from exercise may actually produce an initial increase in weight. Consequently, a weight reduction diet may produce the desired results very slowly, and progress may be hard to measure. Many people, by contrast, expect rapid, dramatic changes in their condition. Still others expect failure and find this belief confirmed by the slow rate of change in their health. An accurate, rapid feedback mechanism is needed to help patients sustain changes in life style which will lead to sustained weight loss.
It is known that a person exhales acetone in the breath when the body is in a condition of energy deficit, that is, when the body is using more energy than it is taking in through food or beverages. Ketosis is, therefore, an immediate measurable indication that a person is successfully maintaining a reducing diet. See, for example, Samar K. Kundu et al., xe2x80x9cBreath Acetone Analyzer: Diagnostic Tool to Monitor Dietary Fat Lossxe2x80x9d, Clin. Chem., Vol. 39, No. 1, pp.87-92 (1993).
The potential for the use of exhaled breath as a diagnostic tool has long been recognized. Hippocrates taught the physician to be aware of the smell of the patient""s breath, as a clue to the patient""s condition. In 1784 Antoine Lavoisier and Pierre Laplace analyzed breath of a guinea pig, finding that an animal inhales oxygen and exhales carbon dioxide. This was the first direct evidence that the body uses a combustion process to obtain energy from food. Since that time, as many as 200 compounds have been detected in human breath, some of which have been correlated with various diseases.
Detection apparatus for breath components employ varying technologies. Infrared light has been used to measure breath alcohol content by Bowlds U.S. Pat. No. 5,422,485 and Paz U.S. Pat. No. 5,515,859. Sauke et al. U.S. Pat. No. 5,543,621 used a laser diode spectrometer. Other types of lasers and absorption spectroscopes have been used including cavity-ringdown spectroscopy. See, e.g. xe2x80x9cAbsorption Spectroscopes: From Early Beginnings to Cavity-Ringdown Spectroscopyxe2x80x9d B. A. Paldus and R. N. Zare, American Chemical Society Symp. Ser. (1999), Number 720, pp. 49-70. Other techniques include gas-liquid chromatography (xe2x80x9cGCxe2x80x9d), mass spectrometry, coupled GC-Mass Spectroscopy, electrochemistry, colorimetry, chemi-luminescence, gas biosensors, and chemical methods. See, e.g., xe2x80x9cThe Diagnostic Potential of Breath Analysisxe2x80x9d, Antony Manolis, Clinical Chemistry, 29/1 (1983) pp. 5-15, and xe2x80x9cTechnology Development in Breath Microanalysis for Clinical Diagnosisxe2x80x9d, Wu-Hsum Cheng, et al., J. of Laboratory and Clinical Medicine, 133 (3) 218-228 March, 1999. Among the chemical sensors are so-called electronic noses, which rely on an array of detectors to recognize patterns of physical or chemical characteristics to identify components. These sensors may rely, for example, on conductive polymers, surface acoustical wave generators, metal oxide semiconductors, fluorescence or electrochemical detection. Such sensors are commercially available from Cyrano Sciences, Pasadena, Calif., for example, and their use in detecting medical conditions such as pneumonia, halitosis and malignant melanoma has been suggested.
Many of these technologies are complex, expensive and difficult to calibrate. They have not been economically adapted for individual health care use. It has been suggested, however, that self-administered breath alcohol tests could be used (See, Brown et al. U.S. Pat. No. 5,303,575) by multiple individuals at bars or other locations where alcoholic beverages are served to detect a predetermined level of breath alcohol.
We have invented a method and apparatus for helping a patient modify health related behaviors, particularly weight loss and more particularly weight loss for diabetic patients. The method comprises measuring a physiologic parameter correlated to the behavior or condition to be changed, obtaining information on the psychological or emotional state of the patient, correlating the parameter and the information so measured or obtained, and providing information to the patient based on the correlation between said parameter and said state. The physiologic parameter may be a blood component, temperature; cardiovascular condition or pulse rate, a urine component, a physical activity sensor, weight, body fat composition sensor, or a component of the exhaled breath. Preferably the parameter can be measured non-invasively. Most preferably, the parameter is a component of the exhaled breath, in particular, acetone. Information on the psychological or emotional state of the patient may be obtained interactively through a self-administered computer-based questionnaire and may include correlation with past answers to questions, elapsed time in treatment, or trends in the information. The parameter and the information may be correlated through a computer system. Correlation may comprise selecting a response likely to re-enforce positive behavioral change in the patient. Preferably, remote sources of information may also be accessed, as, for example, through a communications connection. An example of such a connection may be an interactive connection to the Internet. Information may be provided directly from the apparatus, or by contact through a physician, health-care provider or support group.
Measuring acetone in exhaled breath to detect a condition of energy deficit presents certain difficulties. The preferred rate of energy deficit is about 500 Calories per day. This is a lower rate than used in ultra-low calorie diets under controlled clinical conditions. Consequently, low levels of exhaled acetone may be expected. Moreover, metabolic rates may vary among persons because of fitness or general state of health, including the progress of a disease such as diabetes. To overcome the difficulties of calibration, patient-to-patient variation, and other problems, we have invented a medical breath-component analyzer, which maintains a database profile of a patient over time. It is intended that a patient use our invention over an extended period so that a baseline status for that patient may be determined. Acute variations from baseline are identified as clinically significant. The acquired data can be reported to the patient using the device at home and transmitted electronically to a physician or health care provider. Alternatively, the data may be maintained at a remote location, such as a website, and accessed by the physician or health care provider as needed. Multiple tests may be provided, including quantitative tests, qualitative tests, and quantitative approximations using qualitative devices. In particular, laser spectroscopy with multiple lasers having different output characteristics may be used on a single breath sample. The merged output of the plurality of lasers can form a template or pattern, characteristic of a particular patient, whereby complex conditions may be more easily recognized. A set of tests is selected for a particular patient, and may be customized to the patient""s condition. If a change in condition is detected, additional environmental and user-supplied information may be acquired to determine if a change is clinically significant.